Method for producing a fiberoptic waveguide

Abstract

A method is described for producing a fiberoptic waveguide with a basic segment ( 11 ) and a phase shift segment ( 12 ), the basic segment ( 11 ) and phase shift segment ( 12 ) having fiber cores (K) of the same form and the fiber cores being aligned at a defined angle (α) to one another. In the method, use is made of an optical fiber ( 1 ) having a fiber core (K) of the abovenamed form, which fiber is twisted at least approximately by the abovenamed defined angle (α) and held fixed in this torsional position. Subsequently, a stress-relief zone ( 13 ) is heated inside the twisted fiber ( 1 ) until the torsion is released inside the stress-relief zone ( 13 ) and the basic segment ( 11 ) is produced on one side of the stress-relief zone ( 13 ) and the phase shift segment ( 12 ) is produced on the other side. In this case, the fixing of the torsional position is maintained until after solidification of the stress-relief zone ( 13 ).

What is claimed is:  
     
       1. A method for producing a fiberoptic waveguide with a basic segment and a fiberoptic phase shift segment, the basic segment and the phase shift segment having fiber cores of the same first form, the fiber cores being aligned at a defined angle to one another, and the phase shift segment being connected to a second fiber via a joint, the second fiber having a core of a second form, that second form being different from the first form, comprising the steps of: 
       using an optical fiber with a fiber core of the first form, twisting the optical fiber by at least approximately the above named defined angle and holding the optical fiber fixed in this torsional position;  
       heating a stress-relief zone inside the twisted optical fiber until the torsion is released inside the stress-relief zone; and  
       maintaining the fixing of the torsional position until after solidification of the stress-relief zone, the stress relief zone separating the phase shift segment and the basic segment of the optical fiber.  
     
     
       2. The method as claimed in  claim 1 , wherein the second fiber is joined to the phase shift segment after the solidification. 
     
     
       3. The method as claimed in  claim 1 , wherein at least approximately a multiple of a fraction of a beat length of orthogonal polarization modes is selected as the length of the phase shift segment. 
     
     
       4. The method as claimed in  claim 3 , wherein the length of the phase shift segment is selected longer than a theoretical desired value of a multiple of a fraction of a beat length of orthogonal polarization modes. 
     
     
       5. The method as claimed in  claim 1 , wherein 45° is selected as the defined angle. 
     
     
       6. The method as claimed in  claim 1 , wherein the optical fiber is connected to the second fiber before the torsion, wherein both fibers are twisted jointly, and wherein the optical fiber is heated at a defined distance from the joint. 
     
     
       7. The method as claimed in  claim 6 , wherein a fiber with an elliptical core is used as the optical fiber, and a fiber with a round core is used as the second fiber. 
     
     
       8. The method as claimed in  claim 1 , wherein after solidification of the stress-relief zone the optical fiber is broken at a defined distance from the stress-relief zone. 
     
     
       9. The method as claimed in  claim 8 , wherein at this broken end the optical fiber is connected to an end of a second fiber. 
     
     
       10. A fiberoptic waveguide comprising a basic segment, a fiberoptic phase shift segment connected in a fashion adjoining the latter, and a second optical fiber, the basic segment and phase shift segment having fiber cores of the same first form, the fiber cores being aligned at a predetermined angle to one another, and the second optical fiber having a fiber core of a second form, which second form is different from the first form, wherein the phase shift segment and the basic segment are produced from a single-piece optical fiber and separated by a stress-relief zone of the single-piece optical fiber having a core of a form that is different from the first form, and wherein the second fiber is connected to that end of the phase shift segment, which is averted from the stress-relief zone. 
     
     
       11. The method of  claim 1 , wherein the phase shift segment and the basic segment of the optical fiber are adjacent to the stress relief zone.